A BEEM study of Schottky barrier height distributions of ultrathin CoSi2/n-Si(100) formed by solid phase epitaxy

The spatial distributions of the Schottky barrier heights of ultrathin CoSi 2 films (similar to 10 nm) on n-Si(100),obtained by multilayer solid state reaction of Co/Ti/n-Si, Co/a-Si/Ti/n-Si, Ti/Co/a-Si/Ti/n-Si and Co/n-Si sys tems, are studied by ballistic electron emission microscopy (BEEM) and spec troscopy (BEES) at low temperature (similar to - 80 degrees C). The barrier heights determined from BEEM spectra range between 520 meV and 700 meV, wi th an approximate Gaussian distribution. The mean barrier heights of the ep itaxial CoSi2/Si contacts are 0.60-0.61 eV, lower than the 0.64 eV for poly crystalline CoSi2/Si contacts. Adding a thin amorphous Si interlayer (1 nm) slightly increases the probability of higher barrier heights, while a thin Ti capping layer (1 nm) has no significant influence on the mean barrier h eight. The BEEM results are compared to those from I-V/C-V measurements.